I don't have a huge problem with the pets not using their buffs/heals/stuns and the like. It'll affect solo play in PvE mostly but maybe that's just a sacrifice that needs to be made.
What is a problem is that I also assume this means they don't use claw/bite/smack or rabid. That's a HUGE nerf to a dps cooldown. A dps cooldown we're going to pot during. A dps cooldown whose dps is nerfed over 60%.
And to compensate... a 15% damage buff to arcane shot?
On paper I realize this might math out (and it does on FemaleDwarf), but the mere fact that we are going to tend to stack Stampede with our pots and trinkets means this becomes a nerf in practice.
Accounting for that in FemaleDwarf with my gear, the Arcane Shot buff would have to be at least 20% to properly compensate.
My proposal, and my preferred solution is to go ahead and remove ability usage from pets in stampede EXCEPT growl (this is very important utility I am unwilling to give up and has ZERO impact on PvP), but buff their damage to 65% of pet damage from 25%. Stampede base damage remains the same but no pet specials i.e. extra buffs/heals/cc. Failing that increase Arcane Shot buff to 20%.
P.S. Totally willing to give a breakdown of my calculations if asked but as they are rather simple, I assume you can figure it out Blizz.